1. Field of the Invention
The present invention relates to an active matrix display device for controlling the amount of current passing through a light-emitting element such as an organic EL element using an insulated-gate field-effect transistor included in each pixel, a driving method for the display device, and an electronic apparatus including the display device.
2. Description of the Related Art
In image display devices such as liquid crystal displays, a large number of liquid crystal pixels are arranged in a matrix form. An incident light transmission intensity or an incident light reflection intensity is controlled for each pixel on the basis of information about an image to be displayed so as to display the image. This is similarly performed in organic EL displays in which organic EL elements are used in pixels. In this case, these organic EL elements are self-light-emitting elements that function differently from the above-described liquid crystal pixels. Accordingly, the organic EL displays have the advantages of achieving image visibility and a response speed both of which are higher than those of liquid crystal displays and requiring no backlight. Furthermore, in the organic EL displays, the luminance level (gradation) of each light-emitting element can be controlled in accordance with the value of a current flowing therethrough, that is, each light-emitting element is a so-called current-controlled element. Therefore, the organic EL displays using current-controlled light-emitting elements are significantly different from the liquid crystal displays using voltage-controlled liquid crystal pixels.
Like the liquid crystal displays, the driving methods for the organic EL displays include a simple matrix driving method and an active matrix driving method. The simple matrix driving method can make the structure of an organic EL display simple, but it is difficult to realize a large-sized and high-definition display using such a method. Accordingly, currently, the active matrix driving method is being developed actively. In the active matrix driving method, a current passing through a light-emitting element included in each pixel circuit is controlled by an active element (a thin-film transistor (TFT) is commonly used as an active element) included in the pixel circuit. Japanese Unexamined Patent Application Publication Nos. 2003-255856, 2003-271095, 2004-133240, 2004-029791, 2004-093682, and 2006-215213 describe the active matrix driving method.